Fix gradle deprecations

[kkris]

While debugging some issue (which later turned out to be #857) I made some changes along the way addressing some gradle deprecation warnings and use some lazy instead of eager APIs.

I does not amount to much, but thought it might be useful anyway to submit as a minor improvement. Feel free to close it though, especially since I did not do too much testing since I am not familiar with all use cases of the library. Tried my best though.

Main changes:

• Migrate from some eager gradle APIs to lazy equivalents (all, withType (without configureEach), getByName), see also https://docs.gradle.org/current/userguide/task_configuration_avoidance.html#eager_apis_to_avoid
• Migrate away from project.buildDir
  ** This change avoids some minor IO during the configuration phase (creating the parent directory of the dependency cache file)

[mikepenz]

Danke dir!

Thank you very much for the PR. I am currently quite busy, so it might take me some time to get to review this one.